The following exemplary embodiments of the present invention relate generally to polyaxial pedicle screws and, more specifically, to a polyaxial pedicle screw that includes a receiver member having a pair of recesses and a pair of locking members for independently securing a rod and a shank.
Polyaxial pedicle screws are commonly used for lumbar fusion surgery. Such screws are configured to receive additional equipment or implants, such as a stabilization rod, either before or after being anchored to the bone via, e.g., a screw or shank. The positioning and alignment of the screw dictates the location and orientation of the additional equipment. In a spinal stabilization procedure, a plurality of pedicle screws are mounted to vertebrae and one or more rods extend between the fasteners so as to immobilize a portion of the spine.
Because pedicle screws are often used for lumbar fusion surgery, precision in the implantation of the screw is of utmost importance. Therefore, robots are sometimes used to assist in the placement and securing of these screws.
Typical polyaxial pedicle screws use a locking cap that threads into a tulip body of the polyaxial pedicle screw to apply a compressive force to the rod and the shank to simultaneously lock the motion of the rod and the shank. Other, more current designs, use a “collet” or other mechanism to independently lock the polyaxial motion of the shank and the motion of the rod.